[Spud] SPUD magic number

[Tom Herbert <[e-mail]>]

Hi,

The SPUD magic number seems like a good idea and in fact I anticipate
that we'll want to adopt this technique in other UDP encapsulation
protocols.

I believe the magic number could be applied in two different ways:

1) A middlebox must match both the UDP destination port and the magic
number before accepting the packet is SPUD protocol. In this case ,
the magic number is used to distinguish SPUD from other arbitrary uses
of a SPUD assigned port.
2) A middlebox matches the magic number in any UDP packet regardless
of destination port and declares it to be SPUD. This is nice because
we would not need to configure SPUD ports on middleboxes, but
increases the chances of misinterpreting something which is not SPUD
at all (a larger magic number size might be warranted).

What is the intended use for this in the SPUD prototype protocol?

Thanks,
Tom